The Promotion Strategies about High School Students’ Intention and Behavior of Physical Activity:Self-determined Motivation’s Contribution to TPB

A prediction model taking Self-determination Theory (SDT) as core, and based on the Theory of Planned Behavior (TPB) was conducted for a better understanding and intervention of high school students' physical activity (PA) .It was hypothesized that self-determined motivation indirectly influences behavioral intention and behavior via the mediation of TPB social-cognitive variables (namely attitudes, subjective norms, and PBC) .Method:Using the psychological test method, 326 high school students (male n=151, age=17.34±0.99;female n=175, age=17.15±0.89) participated the psychological testing including Self-determined Motivation (SDM, α=.812) , Behavioral Intention of PA (BI, α=0.817) , Attitude toward Physical Activity (AT, α=0.893) , Subjective Norms of PA (SN, α=0.813) , Perceived Behavioral Control of PA (PBC, α=0.797) , and PA Behavior Questionnaire.Relation between all variables was tested through building structural equation model.Result:Model fitness indices showed that the hypothesized model was acceptable, 53% variance of BI of PA was explained by SDM via TPB social-cognitive variables (P<0.05) , however, the prediction of SDM via all variables to PA was not good enough (only 6%) .The direct pathway of SDM to BI was0.24.Compared with the prediction to PA behavior, the model rather had a better predictive effect to PA intention.Conclusion:Self-determined motivation has direct prediction effect to intention of physical activity, but the prediction to behavior is not good enough.The TPB socialcognitive variables play the role of partial-mediator between SDM and PA intention.It is suggested that more variables should be explored to bridging the intention-behavior“gap”, and enhancing the explanation power of PA in future studies.